Method and means of perforating well casing and the like



Nov. ,17, l942. F. E 0;NE|| L 2,302,567

ME'IHOD AND MEANS OF PERFORATING WELL CASING AND THE LIKE Filed'Deo. 13,1937 2 Sheets-Sheet l l 29 IJ Z9 52 a y ATTORNEY Nov. 17, 1942. F. E.o'NElLL 2,302,567

MTHOD AND MEANS OF PERFORATING WELL CASING AND THE LIKE Filed Dec. 13,1937 2 Sheets-SheetI 2 l r 39 ,67 i EE 6d- 406 3 6V s! j' W i? A ma O$4,454.42/ 50 v /ZIlN/c/ ff INVENTOR.

ATTORNEY Patented Nov. 17, 1942 METHOD AND MEANS F PERFORATING WELLCASING AND THE LIKE Frenk E. o'Neill, Glendale, Calif., assigner te 1Edith L. oNelll, Glendale, calli.

Application December 13, 1937, Serial No. 179,576.

' 19 claims. (cl. 16s-1) 'This invention relates to oil well productionoperations, and particularly pertains to a method and means ofperforating well casing and the like.

Heretofore the common methods of perforating well casing have been byth'e use of mechanical perforating means and by the use of explosiveperforating means. In my Patent No. 2,034,768, entitled Method and meansof perforating casing, issued March 24, 1936, reissued as Re. 21,085 onMay 16, 1939, the released pressure of well drilling iiuid was utilizedto directly or indirectly produceA a perforating action through a wellpipe. My present invention is concerned with the use of abrasive fluidforced downwardly into a well and directed laterally thereof against thewell casing to create an abrasive action which is continued until thewell casing is perforated and a suitable depth of the surroundinggeological formation is opened up to well fluid flow. It is theprincipal object of the present invention therefor to provide a methodand means of perforating a well casing or treatthe casing may beseveredfwhen the fluid under pressure is discharged therefrom.

It is to be understood in this specification that the terms abrading anderoding are being used interchangeably as referring to the action -1brought about by a jet of fluid, carrying susing th'e same by the use ofa uid mixed with a chemical or containing suspended abrasive solidswhich will act to erode ,the wall of the well casing against which itimpinges, and to clean the mud cake from the wall of the well or toperforate the wall or casing, the said iiuid being delivered to theejecting nozzle under pressure and being directed against the area to beacted upon by means responsive to fluid pressure, 'whereby the eductionend of the ejecting nozzle will be disposed in close proximity to thesurface to be acted upon by the eroding fluid, the said method and meansacting to concentrate a perforating action in certain spots on the wallof the casing, or the like, whereby a direct perforation will be madethrough the casing, or in directing the 'abrading stream of materialalong a path of travel whereby the casing may be slotted or cutl in two.

The present invention contemplates the provision of a string of pipe 'inconnection with which a pump or other suitable means for delivering uidunder pressure thereto is provided, and whereby an abrading or erodingiiuid may be forced down the string of pipes to suitable nozzle means,the nozzle means in one instance being in the form of areciprocatingelement which will act under pressure of the iiuid passingtherethrough to be projected outwardly from its housing and into closeproximity to the casing to be perforated thereby, the nozzle in anotherform of the invention being a movable element by which pended particlesor including a. chemical agent, impinging against a surface in a wellbore, whether that surface be the wall of a, metal well casing or themud sheath which forms upon the wall of a well bore and which must beremoved to permit free flow of cognate uid from the geologicalformation.

Th'e invention is illustrated by way of exarrple in the accompanyingdrawings in which:

Figure 1 is a view in diagram illustrating one manner of installing theperforating structure Within a well casing and operating the same.

Fig. 2 is an enlarged view in section and elevation showing one form ofthe perforating unit as seen on line 2--2 of Fig. 1.

Fig. 3 is an enlarged view in central section through ene form of theperforating unit as seen on the line 3-3 of Fig. 1, and discloses thestructural details of a nozzle unit.

Fig. 4 is an enlarged fragmentary view in central section through one ofthe perforating nozzles indicating it in a retracted position anddesignating it extended by dotted lines.

Fig. 5 is a view in vertical section and elevation showing a form of theinvention in which a rotary nozzle is provided for severing the pipetransversely of its longitudinal axis.

Fig. 6 is a view in transverse section through the cutting structure asseen on the line 6-6 of Fig. 5.

Fig. 7 is a view in side elevation showing the modiiication of the meansfor holding the piston in a retracted position.

Referring more particularly to the drawings I0 indicates fluid pump,such for example as the mud pump in a well, said pump being provided todeliver iiuid under pressure through a conduit I I to a head I2. Thehead I2 is mounted upon a string of tubing or drill pipe I3 which is leddownwardly through' a well casing I4 and with its lower end into theproducing area of the well. This pipe may carry a liner I5 which issubsequently to be perforated.

I rl the form of the invention shown in Figs. 2 and 3 of the drawingsthis perforation is accomplished by producing and projecting lateraljets of fluid from a perforating head generally indicated at I6, andwhich jets or fluid are directed against the liner I5 or casing Il toproduce an abrasive or erosive action. The perforating head structure I6may be held in the well by slips which may be applied at the top of thewell or may be `carried by the perforating head itself as particularlyindicated in Fig. 2 of the drawings. In Fig. 2 of the drawings itwill beseen that the lower portion of the perforating head comprises a pointedmember I1 which has threaded connection with a fluid inlet sub I8. Thisinlet sub is formed with a plurality of perforatlons I9 communicatingwith a central opening 20. Threaded into the upper end of the opening 20of inlet sub I8 is a valve seat element 2| having a threaded portion 2i'extending upwardly into a valve sub 22. A uid duct 23 is formed throughthe valve seat element 2| and is normally closed by a valve ball 24disposed in an opening 22' of valve sub 22. This valve ball is held onits seat by a spring 25 and is adapted to be lifted from its seat whenexternal fluid pressure is applied for a purpose to be hereinafterexplained. The sub 22 has a i central passageway through it leading fromopening 22' and is in communication with a tube 21. Mounted upon thetube 21 as illustrated in Fig.' l of the drawings is a lower collar 23to which bow springs 29 are secured at their lower ends.

These springs are secured at their upper ends to a sleeve 3i) which isslidable upon the tube 21 and which carries a pin 3| operating in abayonet slot 32 by which the sleeve 30 is normally held in its uppermostposition. lPivotally mounted to thev sleeve are' arms 33 which carryslips 34. The slips engage an operating cone 35 by which the slips maybe moved outwardly upon relative movement of the cone with relation tothe slips. At the upper end of the cone lstructure is a threaded pin 35which engages a barrel section 31 of the perforating unit. This barrelsection carries a plurality of nozzle units, one of which isparticularly disclosed in Fig. 3 of the drawings. Here it will be seenthat upper and lower longitudinally extending ducts 33 are formedthrough the barrel 35 and they communicate with cylinder bores 39disposed transversely of the barrel. Each of these cylinder bores isfitted with a piston' structure 40 carrying a nozzle 4|. The nozzleextends longitudinally of the bore and has a tubular portion 42terminating in an outwardly flared conical end portion 43. An outwardlytapered throat 44 is formed in the conical end 43 of the nozzle v4| andcommunicates with a central cylindrical passageway 45 which extendsthrough the tubular portion 42. tubular portion 42 is formed withprojecting lugs 46 which are adapted to bear against the wall of thecasing when the nozzle 4| is in its extreme outermost position, and willprovide a ow space outwardly through which the fluid may flow after ithas impinged against the casing surface. y The outer end of the tubularportion 42 of the nozzle 4| is guided through a threaded disc 41 whichsubstantially closes the rightward end of the cylinder bore 39. Thisthreaded disc may be formed with .perforations 48 which would allowcirculation of fluid through the disc. The conical end 43 of nozzle 4|is mounted with a seat member 49 of the piston 40. The seat member has aThe outer end of the hub 50 through which the tubular portion 42 ofnozzle 4| extends and a disc portion 5| agreeing substantially indiameter with the diameter of the bore 39. A reduced threaded portion 52"receives a packing ring 53 and a piston ring 54.

ternal threaded portion 54' of the ring 54 also receives a strainerplate55. This plate is formed with a plurality of ducts 58 therethrough whichare 'preferably disposed at an angle relative to the longitudinal axisof the bore 45 of the nozzle 4| so the fluid under pressure which isforced through the ducts 56 of plate 55 and into the nozzle 4| will becontrolled in its direction of "flow ang will not create eddy currentsin the throat 44of the nozzle which would tend to abrade the nozzle 4I.It is to be understood that the nozzle is made of alloy metal ofvrelatively great hardness and toughness and that the design and thearrangement of the throat 44 of the nozzle member 4| and the ducts 55through the ,plate 55 will be such as to conduct fluid into thepassageway 45 with the least amount of uid ldisi turbance. A stopshoulder, or other limiting means, such as an internal sleeve 51 may beused to limit the leftwardor retracted position of the,

piston 40 and the nozzle 4|. The piston assembly 40 is held in retractedposition by a spring 58 which is interposed between the disc 41 andthefront face of the disc portion 5| of the piston or may be held in itsretracted position by a spring 59 secured at one end to a bracket 59 onthe piston and at its opposite end to a closing disc 50 which isthreaded into the rear opened end of the cylinder bore 39 as shown inFig. 3. It is to be understood that the nozzle 4| and the pistonassembly 40 here described may be duplicated throughout the length ofthe barrel section 31 and that the cylinder bores 39 may be arrangedwith their longitudinal axes in different radial directions withreferenceto the longitudinal center of the barrel, thus making itpossible to cut a number of perforations simultaneously at differentpoints aroundthe circumference and in the length of a casing or tubing.l

Referring particularly to Fig. 5 of the drawings, it will be understoodthat a sub structure, including the hook wall mechanism as substantiallythe same1as that shown and described with reference to Fig. 1 may beused. In this particular device itis intended to utilize the abrasive orerosive fluids in severing the pipe entirely. The structure includes asub 6| which is threaded onto the upper end ofthe hook wall unit 42.Mounted within a longitudinal bore 5| this sub is the lower shaftportion 63 of a nozzle unit 64. The nozzle unit 64 is provided with anupwardly extending shaft portion 65 which is mounted in a longitudinalbore 65' within a cylinder member 66 carried by the well string or othersupport for the structure. Suitable stulng glands 61 are provided topack the shaft members 63 and 45 and retaining collars 88 and 59 aremounted upon the ends of shaft sections 63 and 65, respectively. Thesecollars 68 and 69 are adapted to hold the entire structure in assembledrelationandpermit the nozzle G4 to revolve on the central vertical axisof the structure. The rotating nozzle 44 as shown in Fig. 6 is formedwith a plurality of radially disposed arms 10 which are curved at theirends so as to provide jet elements 1|, which are disposed at a tangentto the rotating axis of the nozzle unit 64 and will act under fluidimpulse to cause the nozzle structure 64 to rotate and direct the fluidfrom the nozzle jets 1|' in Figs. 1 to 4, inclusive, the structure isassembled as there disclosed and may be lowered into a wel to a desireddepth. When thus lowered the 'springs 29 of the hook wall structure willfrictionally engage the casing I4. When a suitable depth has beenreached the drill string structure is rotated to move the pin 3| out ofthe hooked Cil end of the bayonet slot 32 and to allow the weight y ofthe drill string to act to move the cone 35 downward with reference tothe slips 34 as a pin 3| travels downward in bayonet-slot 32, therebycausing the slips toengage the casing and become set. Fluid underpressure is then forced downwardly through the drill string I3 from thepump I 0. This fluid may be the fluid present in wells at the time ofdrilling and known as drilling fluid, which would have certainabrasive-characteristics due to the suspended solids carried from thewell, or it may be a specially prepared fluid, including a liquid withinwhich special abrasive material in flnely divided forml l is placed.Such a material maybe clean beach or river sand. In some instances itmay be deemed desirable to use a fluid within which erosive material ismixed, such for example as suitable acids in liquid form in which casesthese materials may be used for directly cleaning the mud cake from thewalls of the well or cleaningv perforations in the well casing, as wellas forming perforations in the wall or vthrough the casing. In any eventthe pressure fluid is forced downwardly through the pipe I3 by the pumpI and eventually it is forced into the passageway 38 which communicateswith the various cylinder bores 39. The pistons 40 at such times arev intheir rearmost positions with the tubular nozzle portions 42 retractedwithin the discs 41 until their forward ends are within a shieldedposition. As the fluid pressure is delivered the fluid will act upon theend face ofthe piston 40 and specifically against the face of lthepiston ring 54 and the strainer disc 55. This will force the piston withthe tubular jet 42 longitudinally of the cylinder bore 39 against thecompression action of spring 58 or the tension of spring 59. This actionwill move the tubular stem of the nozzle outwardly until the lugs 46 onits end face abut against the inner surface of the casing or liner oruntil the shoulder 50 on the piston abuts against the disc 41. In theevent that the space between the inner face of the casing, or liner, issufiiciently narrow to cause the end of the nozzle jet 4| to restagainst this fac'e the lugs 46 will provide a space through which thefluid may flow radially as it produces its abrasive action. This willinsure that a perforation 80 will be formed having a diameter somewhatgreater than the diameter of the tubular portion 42 of the nozzle sothat the nozzle 4I will follow into the opening 80 and will thusmaintain intimate relationship between the end of the nozzle and themetal being abraded. The point of the nozzle may also be forced throughthe perforation B0 so as to form an opening in the surroundingformation. It will also be evident that directly at the end of thenozzle 4I a crater 8| will be cut which will be of smaller diameter andwhich will be formed in advance of the larger recess 80. If theabradingor eroding action is continued the cavities 30 and BI will be extendedthrough the piece of metal being acted upon and a perforation will beformed. Further continuation of this action will cause fluid to passthrough the perforations and into the geological It is evident thatsuspended granular solids of a degree of flneness may be used in makingan abrasive fluid which would be suitable for packing the area of thewell around the casing or liner being perforated so that when thismaterial is carried through the perforations made by the abrasion thegranular material will tend to pack the cavity and act as a lter for thefluids which pass from the formation of the well bore and through theperforations into the casing or lining.

In the form of the invention shown in Figs. 5 and 6 of the drawings, thefluid is used to sever the casing. The structure is set within. thecasing in the usual manner and is then supplied with abrasive fluidunder pressure, as previously described, which fluid isy ejected fromthe nozzle tips 'II of the arms 'I0 and will give an impulse rotation tothe structure 64. The fluid will then impinge against the casing as thestructure 64 revolves.

In the event that for any reason it is necessary to establishcirculation within the well bore, such for example as when an emergencymight arise due to the fact that the accumulation of abrasive materialwithin the casing and around the perforating device had caused thestructure to be lodged in place, then circulation could be establishedthrough the valve structure 2|. This is done by delivering fluidpressure to the upper end of the casing I4 and around the drill stringI3, and then forcing the fluid downwardly and inwardly through thepassageways I9 to the duct 23. The upward force will then lift the valve24 allowing the fluid to pass upwardly through the passageway 26 andthen through the passageways 38 to the drill string. Normally it will berecognized that the valve 24 is seated so that the force of fluid withinthe drill string must act against the pistons 40 'and move the jets 4|outwardly and deliver the force of the fluid through the nozzles. Alength of casing represented by the length of the perforating head maybe perforated, at onetime after which the head may be moved to anotherposition and other perforations cut until the desired length of casingis perforated.

It is to be understood that the valve 24 may be eliminated in someinstances' and then the fluid pressure within the casing and around theperforating structure may be utilized to force the nozzles back to their'retracted positions.

It will thus be seen that the present invention provides suitable means,and a suitable method, whereby a well casing or the like may beperforated by the use of fluid under pressure and that this fluid willhavea direct abrasive action which will perforate the casing withoutdepositing objectionable'material in the well bore and making itpossible -for the structure to be used in cutting off pipe, perforatingthe same, conditioning the well, by perforating or removing the mud cakeon the Walls of the well bore, treating it with chemicals and supplyingit with filter packing materials.

While the apparatus is here shown as used with abrasive fluid it isevident that a suitable acid solution might be used at high velocity andpressure as a solvent and eroding agent to clean the perforations or toclean the walls of the well and open up the formation.

While I have shown the preferred form of the invention, and thepreferred method of practicing the same, it is to be understood thatvarious changes might be made in the combination, construction, andarrangement of parts, and in the steps of the method, without departingfrom the spirit of the invention as claimed.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:

1. A method of conditioning a well which consists in placing a casing ina well, thereafter lowering a string of tubing into the well, saidstring of tubing carrying a laterally projecting nozzle, then forcing aliquid carrying abrasive solids downwardly through said string of tubingand outwardly through said nozzle whereby the abrasive liquid will erodean opening through the wall of the casing and then continuing the flowof said abrasive liquid outwardly through the nozzle and the opening inthe casing thus formed until the abrasive elements in the liquid haveaccumulated within the well bore around the casing to form a filter packthrough which fluid from the geological formation may be filtered as itflows into the casing through the eroded perforations.

2. A device for perforating well casing and the like, comprising astring of tubing adapted to be lowered into the casing and connectedwith a source of abrasive liquid under pressure, and a nozzle carried byand in communication with said string of tubing whereby a jet of fluidunder pressure may be directed downwardly through said string of tubingand outwardly through said nozzle to impinge against the surroundingwall of the Well.

3. A device for perforating casing and the like. comprising a string oftubing to be lowered into a well casing, friction means carried by thestring of tubing for holding said tubing in set position relative tosaid casing, a perforating unit carried by said string of tubingadjacent to said friction means and communicating with the string oftubing and mounted to project a stream of fluid laterally from thestring of tubing against the wall of the casing, and means for forcingliquid downwardly through the string of tubing and outwardly throughsaid perforating unit, whereby said liquid will erode an'opening throughthe casing against which it impinges.

4. A device for perforating casing and the like, comprising a string oftubing to be lowered into a well casing, friction means carried by thestring of tubing for holding said tubing in a selected position relativeto said casing, a perforating unit carried by the string oftubingadjacent to the friction means and communicating with the stringof tubing and mounted to project a stream of fluid laterally from thestring of tubing against the wall of the casing, and means for forcing aliquid downwardly through the string of tubing and outwardly throughsaid perforating unit,

whereby said liquid will erode an opening through the casing againstwhich it impinges, said perforating unit including a laterally disposednozzle.

5. A device for perforating casing and the like, comprising a string oftubing to be lowered into a well casing, friction means carried by thestring of tubing for holding said tubing in position relative to saidcasing, a perforating unit carried by the string of tubing adjacent tosaid friction means and communicating with the string of tubing andmounted to project a stream of fluid laterally from the string of tubingagainst the Wall of the-casing, means for forcing a liquid downwardlythrough the string of tubing and outwardly through said perforating unitwhereby said liquid will erode an opening through the casing againstwhich it impinges, said perforating unit including a laterally disposednozzle, and means within said perforating unit for supporting saidnozzle, whereby said nozzle will be moved outwardly from the side of theperforating unit to a projecting position relative to said casing.

6. A device for perforating casing and the like, comprising a string oftubing to be lowered into a well casing, friction means carried by thestring of tubing for holding said tubing vin position relative to saidcasing, a perforating unit carried by said string of tubing adjacentsaid friction means and communicating with the string of tubing andmounted to project a. stream of fluid laterally from the string oftubing against the wall of the casing, means for forcing a liquiddownwardly through the string of tubing and outwardly through saidperforating unit, whereby said liquid will erode an opening through thecasing against which it impinges, said perforating unit including alaterally disposed nozzle, means within said perforating unit forsupporting said nozzle, whereby the nozzle will be moved outi wardlyfrom the side of the perforating unit to a projecting position relativeto said casing, and means for retracting the no'zzle when fluid pressureis relieved.

7. A perforating unit adapted to be lowered into a well casing on astring of pipe, at the upper end of which fluid under pressure isdelivered, said perforating unit comprising a barrel having a fluidpassageway downwardly therethrough, a lateral opening in said barrel incommunication with said fluid passageway, and a nozzle mounted toreciprocate within said lateral opening and through which a pressurefluid is forced.

8. A perforating unit adapted to be lowered into a well casing on astringof pipe, at the upper end of which fluid under pressure isdelivered, said perforating unit comprising a barrel having a fluidpassageway downwardly therethrough, a lateral opening in said barrel incommunication with said fluid passageway, a nozzle mounted toreciprocate within said lateral opening and having a passageway throughwhich a pressure fluid is forced, and a mounting for said nozzle actingto permit reciprocaiion of the nozzle, whereby the pressure of the fluiddelivered to the nozzle'will tend to force the nozzle outwardly towardthe object against which its fluid jet impinges.

9. A perforating unit adapted to be lowered into a well casing on adrill string, at the upper end of which fluid under pressure is.delivered. said perforating unit comprising a barrel having afiuidpassageway downwardly therethrough, a

vlateral opening in said barrel in communication `with said fluidpassageway, a nozzle mounted to cation of the nozzle whereby thepressure of the fluid delivered to the nozzle will tend to` force thenozzle outwardlytoward the object against which its fluid jet impinges,and means for holding said nozzle in a retracted position.

l0. A perforating head for casing and the like, adapted to be mountedupon the lower end of a string of tubing and in communication therewith,the upper end of said string of tubing being in communication with asource of fluid under pressure, said `head comprising a barrel having apassageway therein in communication with the tubing, and a lateral boretherein in communication with the passageway within the barrel, closuresfor the opposite ends of said lateral bore, a piston reciprocatingwithin said lateral bore, a nozzle carried by the piston and projectingthrough an opening in one of said closures,

' whereby when fluid is forced into the cylinder bore and through thenozzle the piston and the nczzlc will be moved longitudinally of thebore to project the end of the nozzle outwardly and toward the surfaceof the object to be perforated.

11. A perforating head for casing and the like. adapted to be mountedupon the lower end of a string of tubing and in communication therewith,

the upper end of said string of tubing being in communication with asource of fluid under pressure, said head comprising a barrel having apassageway therein in communication with the tubing, and a lateral boretherein in communication with the passageway within the barrel, closuresfor the opposite ends of said lateral bore, a piston reciprocatingwithin said lateral bore, a nozzle carried by the piston and projectingthrough an opening in one of said closures, whereby when fluid is forcedinto the cylinder bore and through the nozzle the piston and the nozzlewill be moved longitudinally of the bore 'to project the end of thenozzle outwardly and toward the surface of the object to be perforated,and means for retracting the piston and nozzle when the fluid pressureis relieved.

12. A perforating head for casing and the like, adapted to be mountedupon the lower end of a string of tubing and in communication therewith,the upper end of said string of tubing being in communication with asource of fluid under pressure, said head comprising a barrel having apassageway therein in communication with the tubing, and a lateral boretherein in communication with the passageway within the barrel, closuresfor the opposite ends of said lateral bore, a piston reciprocatingwithin said lateral bore, a nozzle carried by the piston and projectingthrough an opening in one of said closures whereby when fluid is forcedinto the cylinder bore and through the nozzle the piston and the nozzlewill be moved longitudinally of the bore to project the end of thenozzle outwardly and toward the surface of the object to be perforated,and spacing means on the end of the nozzle for contactingthe surface tobe perforated and to hold the nozzle in spaced relation thereto wherebythe flow of fluid may pass from the nozzle. y

13. A perforating unit adapted to be lowered into a well casing on adrill string, at the upper end of which fluid` under pressure isdelivered, said unit including a barrel having a fluid passage extendingdownwardly therethrough, walls forming a lateral opening in said barrelcommunicating` with said Afluid passage, a piston mounted to reciprocatein said lateral opening,

and a nozzle carried by said piston and through which fluid underpressure is forced in a manner t0 move said nozzle relativo to saidcasina.

14. A perforating unit adapted to be lowered into awell casing on adrill string, at the upper end of which fluid under pressure isdelivered, said unit including a barrel having a fluid passage extendingdownwardly therethrough, walls forming a lateral opening in said barrel'communicating with said fluid passage, a piston mounted in said lateralopening, a nczzle carried by said piston, and means for actuating saidpiston to cause said nozzle to move outwardly from said barrel and intodifferent positions relative to said casing.

15. A perfor-ating unit adapted to be lowered into a. well casing on astring of drill pipe at the upper end of which fluid under pressure isdelivered, a barrel associated with said unit having a fluid passagewayin alignment with Asaid drill pipe, walls forming a lateral opening insaid barrel communicating with said fluid passageway, a piston adaptedto reciprocate in said lateral opening, and a nozzle carried by saidpiston and adapted to move outwardly from said opening under thepressure of fluid against said piston and deliver a flow of fluidagainst the surrounding wall of the well casing. y

16. The method of cutting casing within a Well t bore which comprises;positioning a nozzle within the casing, adjacent the place where the cutis desired, and forcing abrasive material from the top of the wellthrough the nozzle against the tubular member extending down into thewell to the area to be perforated, means for closing the lower end ofthe member against downward ow of liquid therethrough, and nozzles insaid member opening outwardly, therefrom to direct against localizedareas of the casing and adjacent formation an abrading liquid pumpeddownwardly within the tubular member, said nozzles having outwardlyconverging openings whereby the pressure head of the abrading liquid isconverted to velocity head to increase the abrading action of theliquid.

19. The method of severing casing within a bore hole comprising thesteps of lowering into the casing a tubing string having an outwardlydirected nozzle therein, charging a circulating fluid with abrasiveparticles, pumping the charged fluid downwardly within the tubing stringand outwardly through such nozzle to impinge upon a localized area ofthe casing, and rotating the tubing string so that the casing will besevered by the abrading action of the uid.

FRANK E. ONEILL.

